While injection devices and needle systems have been in use for many years, recent developments in minimally invasive procedures require needle systems capable of accessing distant or difficult to access regions of the body, capable of delivering agents of high viscosity (e.g., chemo-embolization agents, depot drug formulations, fillers, etc.), capable of delivering agents with low shear (cells), and/or capable of delivering agents at high flow rates.
Injection devices may include a simple needle attached to a syringe, a needle assembly designed to pass through the working channel of an endoscope or catheter or other minimally invasive introduction device, and/or a needle incorporated into a more complicated device. In such cases, injecting viscous fluids into a body cavity, space, or tissue involves a number of unique challenges compared to injecting non-viscous fluids. These challenges/problems include, among others, efficient movement of the fluid with minimized pressure requirement and/or shear force, clog prevention, clog elimination/clearing, multiple sequential injections, injection of one or more additional, in some cases less viscous, fluids sequentially or intermittently without significant cross contamination, etc.
Further, the need for flexible catheter-based needle injection systems has increased in recent years given the proliferation of potential injectable materials (e.g., stem cells, ablative agents, chemotherapeutic agents, bio-polymers, other pharmaceuticals, etc.). The benefits of these materials frequently depend on the ability to precisely target their delivery to specific anatomical locations, which depends on many common catheter challenges most especially flexibility. Additionally, in the case of viscous fluids or high volume injections, the need arises for a design to balance two conflicting objectives—a small needle to minimize trauma, etc. and a large diameter to enable ease of injection, e.g., to maximize or permit adequate flow at a reasonable pressure, e.g., which can be easily generated by a handheld syringe.
Thus, traditional needles and injection systems have been shown to have a number of potential drawbacks. Therefore, apparatus and methods that facilitate injection of such materials would be useful.